Pelorus



- Oct. 9, 194 5. I c. A. cLAK 2,386,542

J um LIL.

' PELORUS Filed June so, 1943 s shee ts-sneet 1 gwuwwbom C; A. CLARK PELORUS Filed June 1945 3 Sheets-Sheet 2 [Zades Oct- 9, 1 I c. YAUCLARK I PELORUS FiledJune 50, 1943 3 Sheets-Sheet 3 latented Oct. 9, 1945 PELORUS Charles Arthur Clark,- Portland, reg., assignor to Leupold & Stevens Instruments, Portland,

0reg., a partnership Application June so, 1943, Serial No. 492,969 7 Claims. (01. 240-21) i This invention is directed to animprovement in, a navigation instrument of the pelorus type,

wherein parallax is avoided, and wherein permanency of adjustment and illumination of th dial, and ease of manipulation in use, are essential features of the improvement. v

An essential characteristic of the improvement is the provision of an indestructible opaque compass card, accurately centered and rigidly mounted, eliminating by its indestructibility the objectionable fragility of the glass or like transparent card usually employed in previoussimilar structures.

A particularly important feature of the improved construction is the control of the illumination of the card to a substantially limited area directly'beneath the alidade sight wire, to restrict and confine'the illumination to the reading area, and to utilize the alidade as the element for directing the illumination to thus insure restriction of illumination to the section ofthe card graduation being utilized at any particular time. The invention is also directly concerned with themountings, adjustments, and selective locking of the operative details, to provide for ease of manipulation, certainty and permanency of adjustment.1 V

A typical form of the improved instrument will be described in detaiLand is illustrated in the accompanying drawings; in which:

, -Figure'l is a planview of the improved instrument. s Figure 2 is a verticalsection of the same. Figure 3 is a plan view with the alidade removed, showing particualrly the light-passage openings for controlling the passage of light rays to the alidade.

Figure 4 is a bottom plan View of the alidade. Figure 5 is a section on line 5-5 of Figure 2. ,Figurefi is a section on line 6-6 of Figure 2. Figure 7 is a similar view of the rear sight vane. Figure 8 is a section on line 88 of Figure 7. Figure 9 is a detail in elevation,, showing the mounting of the outer gimbal ring in the arms of the supporting yoke, and T Figure 10 is a detail in elevation, partly in section, showing the mounting means for the inner gimbalring.

The improved instrument includes a supporting yoke I, the upstanding arms 2 of which extend from a central head 3, to be removably secured to'an appropriate cap 4 by a set screw 5, said cap being secured at the end of an appropriate standard-ortubular support as shown by dotted lines in Figur '2. -Cooperating pins and depressions 6 0n the respective members serve to accurate]? position and. predetermine the set of the instrument.

The instrument proper is supported on an outer gimbal ring 1, having diametrically opposed pins 8, flattened on one side, as at 9 in Figure 9. The upper or free ends of the yoke arms 2 are formed with hearing slots Ill, which are open at their upper ends, with the upper portions of the walls spaced to just permit the passage of the minor diameter of the pins 8. The lower spacing and shape of the walls of the slots ID are formed to receive and act as a free bearing for the maximum diameters of thepins, all as shown more particularly in Figure 9. The outer gimbal ring is thus freely, supported in'the yoke arms and locked against separation except when the plane of such ring is in the plane of the arms 2.

The inner gimbal ring H is rotatably supported in *the outer gimbal ring 1 at diametrically opposed points equally spaced from the pins 8 by pivot pins [2, which are threaded into the outer ring 1 and secured therein by lock nut l3. The pins are provided with appropriate pivot terminals to seat in openings M in the inner ring II. This detail is more particularly shown in Figure 10. The inner gimbal ring is thus mounted for universal movement.

Inner ring II is provided with inwardly-extending spokes l6'which in turn support a cen-' tral well member l5. stantially closed at the bottom I1, and open at the top, with a completely closed annular side wall [8 of predetermined height. The bottom of the well is formed to receive a light socket I 9, for a removable light bulb or other light light source 20. Thus the light bulb 20 is disposed entirely within the well; A light switch 2| is removably secured to the under side of well member 15 and bottom of the well to a height just below the horizontal plane of shoulder 27.

plate 28 having a central opening of substan- A transparent tially the same diameter as that of the hollow post 26 rests on shoulder 21, overlying the light Well member I5 is subbulb 20. Secured in hollow post 26 is a tube 26A which passes through the central opening of the transparent plate 28 and rises substantially above the horizontal plane of the gimbal ring said tube being threaded at its upper end. A hollow cap 29 embraces the tube 26A, passes through the central opening in the transparent plate 28, and restson the. projecting. end. of the hollow post 26; The cap; 29 .is also. circumferentially enlarged above the plate 28 to bear on said plate at 30 and the upper surface of said cap is provided with an annular recess 29A.

A compass card 3| of opaque material such as metal, preferably, but not necessarily, of. nickel, silver, is provided with a central opening. toreceive a nipple 36 to which the card 3| is secured by nut or ring 33, the card being held or clamped between the nut or ring 33 and a circumferential enlargement 31 of the nipple 36. The nipple 36 and the card 3| slip over the tube 26A and the peripheral.- edge of: the card isseated'. in an annularr recess or shoulder 32: in the inner gimbal ring The nut 33 rests within the recessZSA of cap 2 9, the central: area. of. the card- 3h resting on-the uppersurfaceof. thecap 2-9.. Theunvder. surface of" the cardz bearsialso onthe upper.- edge of! the side wall: |z8- of theWBHi and: forms: at this; point; indicated at. 3.4;, a sealing; barrier against. light. leakage from the well member; The upper surface of the; card; is appropriately marked; ULS. Navy type mar-kings being showni Thenipple Sfixextendsabove the'card. 34% as at138 and. is externally: threaded-t for a; purpose. which will: be explained hereinafter.

The card in thearea overthewellmember I; lSfOI'mEdi withilight passage openings35; These. are shown in. annular series. of" relatively different. diameters, as miligured, but-variationslare. cona. templatedl. These openings provide the sole light-nay. escape from. the. well;

An alidade. 3395 is; formed with. a central; portion: Althaving an opening 4d. to.recei.v.e nipple 36. The central: portion 40.; circular. in. plan, has. an annular; depending flange 42E on. its lowersurface. substatially commensurate with the diameter. of the upper-edge of-:- the wall: |:B of the well? member' The alidade 39 has diametrically-opposed imtegral arm. extensions 43". andl M, the. former constituting; the forward armin use, while the latter is the reararm. The arm, 4.3: isiformed at. it's, free end with a sight opening 415i of: nearly the fullwidth of. the; arm butof-rlesslengththan the length: of: the, arm. Thesight: opening 455 is bridged centrally and: longitudinally by a. sight wire: 45,. terminally secured: to: the arm beyond the. opening;v which. sight; wire, while preferably of: nylon,. may be on hair orfine wire;

' The lower surface of 'the arm. 43; including am appropriate area of theunderside of the central. portion- 40. of the alidade, is cutaway at 41; to. for-n1; a light channel. The lightchannel; is; pref-- erably arched, as in; Figure 61 It opens. at. its: end: remote from the; center 4n directly. to. the

sight: opening 45, and terminates short. of the opening 4! in. the center,- being gradually re. duced in depth within the area of the center; as shown in Figure 4. The lower surface: or the alidade arm 44: is flat. and. arranged to just; clear, the card 3|, the: arm; being formed; with. a sight openin 415., as shown.

The: outer-or free ends of the alidade armsa-re provided with upstanding. walls 48 and. 49 respectively. The walls rise above. the upper surfaces. of the. respective: arms43' and; and support therespective sighting vanes 50 and 5|, respectively. The vane 50 is hingedly connected at 52 for swinging in the plane of the arm in a direction towards the arm 5| and limited to a vertical position in the opposite direction. This vane 50 is of more or less conventional form having a relatively wide longitudinally-ranging slot 53, bridged, by a central longitudinal hair line 54.

Theusuallevel: 55 is carried, preferably removably, in clips; and hingedly mounted at 56, immediately above the level, is a frame carrying a dark glass mirror 51, adapted to cooperate with the sights in the usual manner. The bubble is directly in the, line of vision of the observer and can. befully seenwhile making a sight and without, change of, vision direction.

The vane 5| is hingedly connected at 58 to the Wat-11 49 being movable inwardly toward vane 50 but limited to a vertical position in outward movement. This vane 5| is also more or less conventional, and formedyas shown in- Figures 7- and 8; with a longitudinal arcuate depression 59; said depression terminating in a narrow slot' filh A particularly important feature of the present invention resides inthe formation of the alidade, whereby the visible-lighted area is confined tothe sight opening 45 and the proximate lower area of. the sight vane 50. The described arrangementxof the-card andalidade makes clear that the light raysfrom the bulb 20' can only pass beyondthe'well I5 through the opemngs in the card, and that beyond these openings, the only possible light path is through the light channel 41 The light rays: passing toand through the channel" 4' reach the sight op nin and: illuminate thedialarea, of the card 3 for abo-ut twenty degrees: of the are directly be-v neath thesight wire 46 All other light pas Lsagesto the reading surface of the card are bears on: the alidade to hold the latter securely.

but. removably, against the card 3:|\ attheflange 42 and also against the circumferential enlarge.-.

ment 3.1 of the: nipple. 36.. A further securing member or nut. 64* is; threaded to. the exterior of. that portion of the tube: 25A which extendsv above the nipple 3.61to-ho1d; the nipple 3 5 .up,on the tube 26A and thus secure the alidade and the card 3|- to the gimbali ring lat and thewell member I5.

The. illumination is. controlled by a plunger 6 slidable within the tube 25A. The plunger con.- tinues through; the tube 26A and: into the lower end of the hollow post 26 where it. cooperates. with and: controls the switch 21'. The. plunger Gil may continue through the base of the well; member L5 to comein: contact. with. any provided micro-switchor-may, asshown. in Figure 2, come in contact with the plunger of the, switch 2| within. the: lower end Of. the hollow post. 2.6..

Theswitch 21. may be of any desired construction, as for example a micro-switch such as shown.

in- Patent. No. 1,960,020,. dated May 232,v 1934, or may; if desired, be arranged to provide such selective control of the current as will govern,v within. limits; theiintensity; or the. light; at the: sight; openlug-45;. The upper end of switch plunger 6|. has;

inoperative position on securing member 64 as shown in Figure 2.

The card 3| which is an important feature of the present invention is as previously pointed out,

that the means for illuminating the card as com- Y pared with the usual method of illuminating and directing the light through a glass or transparent card, has the distinct advantage of avoiding any error in viewing the markings of the card with respect to the sight wire, such as reflected or false images, found with use of a glass or transparent card, and also avoids the incidental parallax found with the use of a glass or transparent card. Since illumination is provided for only a very small area of the card and the light source is otherwise shielded, the small amount of light which escapes is only visible within the immediate vicinity of the instrument. This is particularly advantageous when thepelorus is used out in the open on the decks of shipswhich desire to travel without any light whatsoever revealing the ships position.

The operation and use of the improved pelorus does not difier materially from conventional uses, and needs no detailed description.

In general detail and as productive of more eificient coincident operation, it will be appreciated that the relatively large central bearings of the card and of the alidade, together with the edge support of the card, lend to unusual steadiness of the parts in operation. The means for securing these parts separatively and relatively is so simplified as to provide for convenient necessary operative steps while facilitating independent removal for cleaning. Furthermore the immediately adjacent relation of the card graduations and the alidade sight wire obviously insures more accurate reading with less liability of error such as resulting from parallax.

It is contemplated that the light-directing surfaces, particularly that of the alidade, will be sufficiently reflected through proper finish of.

metal surfaces. However, if desired, the said surfaces, including the inner well surface, may be painted a glossy white The under surface of the alidade center 39 may, as shown in Figure 4, be provided with light-directing recesses or deflectors 66 channelled within the under surface and shaped and disposed to assist in directing the light passing through the openings 35 in the card, toward the light channel 41' of the alidade.

It will be noted that the parts are so fitted together as to provide a waterproof housing for the light source and to shield the light-transmitting annular edge, a compass card of metal adapted to overlie and bear on the annular edge of the well, the edge of the card being'in bearing contact with the ring, the card within the area of the annular edge being formed with concentric rings of openings for light passage therethrough, an alidade mounted above the card and having a center formed to surround said card openings and overlie said card openings, said alidade having diametric arms integral with the center and formed with sight openings, one of said arms being formed in its lower surface with a channel leading from the sight opening of that am to and within the alidade center for light communication with the openings in the card.

2. A construction as defined in claim 1, wherein the channel in the alidade arm is of arcuate cross-section, and wherein the defining. edges of the channel in the alidade rest on the card to prevent card illumination beyond such arm.

3. A construction as defined in claim 1, wherein a casing is secured to and extends below the well, a switch secured to said well and arranged in said casing, a, manually-operable switch controlling element extending through the well, card, and alidade center, and means concentric with said element for securing the card and alidade rigidly in any desired relation relative to the rin and to each other.

4. In a pelorus including a support, an opaque card having calibrations on its upper surface, said card being mounted on said support, a, light source below said card, said card having light passages therethrough adjacent its center, an alidade, said alidade having-an opaque recessed hub portion rotatable about the center of the card, said hub overlying the light passages of said card and being peripherally interrupted to direct the light passing upwardly through said card to a single sector thereof, said alidade also including a pair of radial arms extending in opposite directions from said hub, one of said arms being in registry with the interrupted portion of said hub and serving to shield the sector of light except at the calibrated portion of the card.

5. In a pelorus including a support, an opaque card having marginal calibrations, said card being mounted on said support for rotation in a horizontal plane, a housing mounted on said support below said card, the top of said housing and the under side ofsaid card defining therebetween a light seal, a light bulb in said housing, a normally open micro switch controlling the flow of current to said light bulb, said micro switch be ing located in said housing, a switch operating rod extending upwardly from said micro switch through the center of said card to a point thereabove, said card having light passages therethrough adjacent its axis of rotation and an alidade, said alidade having an opaque hub portion recessed on its under side; said hub portion overlying the center of the card with its recessed portion registering with the light passages through the card, said hub portion being peripherally interrupted to confine the light from the recess to a sector of said card, said alidade also including a pair of radial arms extending in opposite directions from said hub, one of said arms being in registry with the interrupted portion of the hub and serving to shield the sector of light except at the marginal portion of the card.

CHARLES ARTHUR CLARK. 

